Magneto-optical disk devices have been noted as devices which permit overwriting and further realize high-density and large-capacity recording and/or reproducing operations. At present, international standardization with respect to those devices has been under consideration, and some models for practical applications have been sold on the market, which may be referred to as the first generation of those devices. Further, the technological development of magneto-optical disk devices has been rapidly carried out with a view to achieving a higher speed of operation and better functioning of the devices.
Among those studies of the devices, the one which is most actively engaged in is that of overwriting technique for enabling higher recording speeds. Overwriting is one of the recording methods wherein new information can be written directly on a recorded area of a recording medium without the necessity of initializing the area bearing previous information beforehand. In the aspect of magneto-optical recording, so-called magnetic field modulation method is considered as a prospective overwriting technique. In the magnetic field modulation method, an auxiliary magnetic field is applied to a portion on a recording medium irradiated by a light beam such that the direction of magnetization is inverted according to information to be recorded. In principle, the mechanism for generating the auxiliary magnetic field includes an electro-magnet.
Meanwhile, conventionally electro-magnets of winding type are suggested in constituting the auxiliary magnetic field generating mechanism (see Japanese Patent Laid-Open Publication No. 279504/1987 (Tokukaisho 62-279504)). However, electro-magnets of this type present problems that it is difficult to obtain high speed inversion of the magnetic field in accordance with information to be recorded because of high impedance of the coil and that considerably large power consumption is necessary to apply an enough magnetic field to a recording area since an efficient application of magnetic field to the recording area is difficult to achieve.
Therefore, in order to provide high-speed switching of the magnetic field in the above-mentioned auxiliary magnetic field generating mechanism, floating type magnetic heads are proposed (see Jpn. J. Appl. Phys., Vol. 26, (1987) Suppl. 26 - 4, pp. 147-154 by T. Nakao, M. Ojima, T. Miyamura, S. Okamine, H. Sukeda, N. Ohta and Y. Takeuti). As the floating type magnetic head, a magnetic head which is miniaturized as small as that for use with a hard disk is adopted. Further, the floating magnetic head is designed so as to float above a rotating magneto-optical disk, having a gap of substantial several .mu.m to several tens of .mu.m in between.
As illustrated in FIG. 4, the floating type magnetic head normally includes a slider 1 for permitting sliding movements with a floating state above a magneto-optical disk (not shown) and a magnetic head 4 having a magnetic core 2 and a coil 3. The magnetic head 4 is fixedly secured to the slider 1 from the outside at the end portion thereof from which an air stream flows out when the slider 1 slides with a floating state. The reason why the floating type magnetic head can float is that an air pressure is produced by the air stream flowing into a contact surface between the magneto-optical disk and the slider 1 due to the rotation of the magneto-optical disk. A predetermined gap between the magnetic head 4 and the magneto-optical disk is maintained through a mechanical balance between the above air pressure and a pressure applied by a suspension, not shown, whereto the floating type magnetic head is secured, so as to depress the slider 1 to the magneto-optical disk. Overwriting operation for information is performed by inverting the direction of the magnetic field according to information to be recorded with the floating state of the magnetic head 4.
However, in the structure as described above where the magnetic head 4 is fixedly secured to the slider 1 from the outside at the end portion thereof, so-called head crash might occur. Here, head crash is a trouble caused by a fact that when on the surface of the magneto-optical disk there exists dust or a projecting object greater than the gap between the magneto-optical disk and the magnetic head, the magnetic head 4 is damaged due to its contact with the dust or the projecting object.
Further, in magneto-optical devices, in order to effectively apply a magnetic field to a recording area, it is important to conform the center of the magnetic pole of the magnetic head 4 to the center of a light beam focused on the disk by an optical head, not shown. Here, as illustrated in FIG. 5, in a recording, reproducing, or other operation, the center of the magnetic pole of the magnetic head 4 being positioned above a track 6 formed on the magneto-optical disk 5 is assumed to move linearly in the radial direction toward the circumferential side while relatively moving above the magneto-optical disk 5 in a rotation direction. (O' in FIG. 5 represents the center of the magneto-optical disk 5.) In this case, the direction of an air stream at the center of the slider 1 varies depending on an instantaneous position in a radial direction on the magneto-optical disk 5. This will be obviously shown by comparing an arrow B located at an inner section of the magneto-optical disk 5 with an arrow C at an outer section thereof. The floating characteristics of the slider vary according to the direction of the air stream, and consequently the gap between the magnetic head 4 and the magneto-optical disk 5 changes depending on an instantaneous position in a radial direction on the magneto-optical disk 5. This causes an adverse effect that intensity of a magnetic field to be applied by the magnetic head 4 might vary undesirably. In other words, a magnetic field should be applied by the magnetic head 4 right onto the central position of an optical beam projected on the magneto-optical disk, that is, an access position where recording is to be performed; however, in the arrangement described above, intensity of a magnetic field to be applied by the magnetic head 4 is caused to change depending on an instantaneous position in the radial direction on the magneto-optical disk, thereby presenting a problem that accuracy of recording is adversely affected.